Cytokine-neuroantigen (NAg) fusion proteins represent a novel therapeutic platform for the treatment of multiple sclerosis. Two fusion proteins will be the focus of the proposed research;interferon (IFN)-beta-NAg and granulocyte-macrophage colony-stimulating factor (GMCSF)-NAg. Previous research in the Lewis rat model of experimental autoimmune encephalomyelitis (EAE) showed that both were effective NAg-specific tolerogens when administered before EAE induction. Both also halted progression of EAE when administered after disease onset. The main purpose of this proposal is to address mechanisms by which these fusion proteins act as tolerogenic, therapeutic vaccines (TTV) in murine EAE. The hypothesis is that TTV function by cytokine-mediated conditioning of APC and the consequent targeting of the tethered NAg to those conditioned APC. We also hypothesize that the beneficial action of these TTV is due to desensitization of effector T cells and expansion of regulatory T cells. The proposal is comprised of four specific aims. These aims will assess (aim 1) whether TTV require specific interactions of the cytokine domain with cytokine receptors to elicit tolerance, (aim 2) whether TTV inhibit encephalitogenic Th1 and Th17 effector T cells, (aim 3) whether TTV desensitize myelin-specific T cells of the transgenic 2D2 encephalitogenic repertoire, and (aim 4) whether TTV elicit expansion of regulatory CD4+ T cell subsets. Overall, the project is designed to advance the development of a TTV as a neuroantigen-specific intervention to control and reverse multiple sclerosis, a devastating disease that afflicts nearly 350,000 Americans and over 2 million persons in the western world. PUBLIC HEALTH RELEVANCE: The project is designed to advance the concept of a neuroantigen-specific, tolerogenic vaccine for treatment of multiple sclerosis. Tolerogenic therapeutic vaccines comprised of recombinant IFN-beta or granulocyte-macrophage colony-stimulating factor (GM-CSF) fused to particular neuroantigens will be tested for prevention and treatment of autoimmune demyelinating disease in murine models of experimental autoimmune encephalomyelitis. The goal is to advance a new therapeutic vaccine for neuroantigen-specific treatment of multiple sclerosis.